1. Field of the Invention
This invention relates generally to throttles for controlling flow through intake systems of internal combustion engines, and more specifically to a throttle body having a wedge that is snap-fit to a throttle blade.
2. Background Information
Spark-ignited, fuel-injected internal combustion engines enjoy extensive usage as the powerplants of automotive vehicles. A representative intake system for such an engine comprises a throttle body that has a through-bore within which a throttle blade, or throttle plate, also sometimes referred to as a butterfly, is disposed. The throttle blade is fastened to a cylindrical shaft whose axis is substantially coincident with a diameter of the through-bore. The shaft is journaled on opposite wall portions of the throttle body for motion about its own axis. An actuator that is external to the through-bore selectively positions the shaft about its own axis, to thereby selectively position the throttle blade within the through-bore over a range of positions spanning a closed throttle position and a full open throttle position.
Various throttle bodies and throttle blades are documented in patent, and other, literature. A throttle blade may be a flat metal plate that has either a circular or an elliptical shape depending on the angle that the blade makes with the longitudinal axis of the throttle body bore when the blade is in closed position. The closed position of a blade that has a circular shape will be at a right angle to the bore axis while a blade that has an elliptical shape will assume closed position at an angle that is not at a right angle to the bore axis.
It is known to add features to a flat metal blade for imparting certain desired characteristics to a throttle body. For example, a lip seal that is applied to the perimeter of a blade may provide sealing of the blade to the throttle body bore when the blade is closed. It is also known to affix an element to a face of a throttle blade for imparting certain flow restriction characteristics when the blade is open. A wedge that is disposed on the upstream face of a blade is an example of one such element. Heretofore, such elements have been applied by various techniques such as injection molding of synthetic material directly onto blades.
Different engine models may require throttle bodies that have different flow restriction characteristics. Throttle bodies that have blades of the same size can be endowed with different flow restriction characteristics by disposing wedges of different shape and/or size on their blades. Because of the ability to change the flow restriction characteristics of a throttle body simply by changing the shape and/or size of the wedge, different throttle models may share a number of common parts other than the wedges. It is believed that this can provide certain manufacturing advantages to a mass-production maker of throttle bodies.
The present invention relates to a novel construction for a wedge and how the wedge is associated with a throttle blade of a throttle body. It is believed that the construction provides certain manufacturing advantages because the wedge is fabricated by itself using a suitable process, such as injection molding, and thereafter is associated with a throttle blade without the use of separate fastening devices. The wedge is disposed on one face of the throttle blade and includes self-attachment features that allow it to snap fit to the throttle blade. The self-attachment features comprise barbed projections that pass from the body of the wedge and through holes in the blade to catch the margins of the holes at the opposite face of the blade. The barbed projections are formed during the molding of a wedge.
Accordingly, a generic aspect of the invention relates to an assembly for selectively restricting intake airflow into an internal combustion engine comprising a throttle body having a bore through which intake flow passes and a throttle blade disposed within the bore for selectively restricting the flow through the bore. The blade comprises one or more through-holes extending between its opposite faces. A wedge comprises a body having opposite non-parallel faces one of which is disposed against one face of the blade. One or more self-attachment features extends from the one face of the wedge body through a respective through-hole in the blade and comprises a barb that catches the opposite face of the blade at the margin of the respective through-hole.
Another generic aspect relates to a wedge for attachment to a throttle blade of a throttle body for selectively restricting intake airflow into an internal combustion engine. The wedge comprises a wedge body having opposite non-parallel faces, one of which is adapted to be disposed against one face of the blade, and one or more self-attachment features that extends from the one face of the wedge body and is adapted to pass through a respective through-hole in the blade, and that comprises a barb adapted to catch the opposite face of the blade around the margin of the respective through-hole.
Still another generic aspect relates to a method of assembling a wedge to a throttle blade. Self-attachment features that extend from a body of the wedge are aligned with through-holes that extend between opposite faces of the blade. The wedge and the blade are advanced relatively toward each other to introduce free distal ends of the self-attachment features comprising barbs into the through-holes and cause the self-attachment features to resiliently flex as the free distal ends are increasingly passed through the through-holes. The advancement continues until the body of the wedge abuts the one face of the blade and the barbs have passed completely through the through-holes so as to allow the flexed self-attachment features to relax and catch the barbs on the margins of the through-holes at the opposite face of the blade.
Other general and more specific aspects will be set forth in the ensuing description and claims.